Perineum compression during EAUS enhances visualization of anterior anal sphincter defects

Abstract

Objective: Endo-anal ultrasound (EAUS) can detect anal sphincter injuries. However, anterior external anal sphincter (EAS) defects can be difficult to define. We assessed different EAUS techniques to determine if any particular method improved defect identification. Method: Ninety females with faecal incontinence were prospectively studied. Wexner faecal incontinence scores were obtained. All patients underwent anorectal manometry and EAUS using three different techniques: standard, digit-assisted (gloved finger pressing on posterior vaginal wall) and balloon-assisted (standard balloon inflated into the vagina). The three techniques were assessed by comparing defect characteristics (detection, angle, edges and scar tissue), and perineal body thickness. All measurements were performed at the mid anal canal level. Results are expressed as medians (IQR). Results: Standard EAUS (S-EAUS) identified a sphincter defect in 54 patients. Digit assisted EAUS (D-EAUS) and balloon-assisted EAUS (B-EAUS) ultrasound revealed a sphincter defect in additional 11 and 9 patients respectively compared to S-EAUS. Correlation of maximum squeeze pressure with EAUS findings improved on D-EAUS and B-EAUS. The defect angle was significantly wider with D-EAUS and B-EAUS [S-EAUS 90°(63-97), D-EAUS 100°(81-101.5), B-EAUS 100°(80-105), P = 0.0005]. The perineal body was significantly thicker when measured with B-EAUS [D-EAUS 9 mm (7-10) vs B-EAUS 10mm (8-11), P = 0.0005]. Inter-observer agreement was comparable [S-EAUS (K) = 0.677, D-EAUS (K) = 0.658, B-EAUS (K) = 0.601]. Conclusion: EAS anterior defect detection and definition on EAUS may be improved by the demarcation and gentle pressure on the posterior vaginal wall. © Journal compilation © 2009 The Association of Coloproctology of Great Britain and Ireland.